Wire storage cubes (you can get them from Target, HERE). This cage is made with 2 and a half packs of the cubes; so about 10.
Zip ties for a more sturdy construction. Enough to connect each cube to each other and to connect all the major joints. The owner purchased 150 zip ties.
Binder clips to hold together the panels that you will want to use as doors.
Chloroplast for the bottom of the cage so the rabbit isn't walking on wire (optional). This can be purchased at some local printing stores.
Fleece to cover the chloroplast (optional). Makes it easy to take out and wash, and keep the cage clean! This can be purchased from craft stores.
And I think you guys can figure out how to design it (anyway you want!), and put it together :)